Bending machine



Aug'. 24, 1943.

P. F. MAIZE l 2,327,440

BENDING MACHINE Filed Dec. 2, 1940 5 Sheets-Sheet 1 27 525 ATTORN EYS.

Aug. 24, 1943. P. F. MAlzE BENDING MACHINE Filed Dec. 2, 1940 3 Sheets-Sheet 2 2 jid Aug. 24, 1943. P. F. MArzE 2,327,440

BENDING MACHINE Filed Dec. 2, 1940 3 Sheets-Sheet 5 INVENTOR ATTORNEY-5v Patented Aug. 24, T943 BENDING MACHINE Paul F. Maize, Detroit, Mich., Manufacturing Company,

poration of Michigan Application December 2, 1940, Serial No. 368,200

(Cl. 15S- 33) 30 Claims.

This invention relates to bending machines and more particularly to machines adapted to bend relatively long workpieces to three-dimensional curvature.

One of the objects of the present invention is to provide an improved bending machine for bending to three-dimensional curvatures relatively long work pieces, such for instance as window frame moldings for motor vehicle bodies.

Another object of the present invention is to provide an improved bending machine for bending various moldings, said machine being provided with a bodily movable form plate.

A further object of the present invention is to provide an improved bending machine for bending various moldings to three-dimensional curvatures, wherein bending of the workpiece is effected by simple relative movements of the form plate and pressure shoes. In conventional structures very complicated movements of form plates, produced by various cams and templets, have been resorted to in order to produce bending of the workpiece to three-dimensional curvatures. This necessitated provision in such conventional structures of very complicated mechanisms for actuating form plates and made each one of such machines suitable for bending workpieces to only one predetermined curvature.

A further object of the present invention is to provide an improved bending machine having a movable form plate, in which complicated movements of the plate and expensive mechanisms producing such movements are eliminated.

A still further object of the invention is to provide an improved bending machine which can be adapted with very few changes'for bending workpieces to many different curvatures.

It is an added object of the present invention to provide a. bending machine of the foregoing` character which is simple in construction, de-

pendable in operation, compact in construction, and relatively inexpensive to manufacture.

Other objects and advantages of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

Fig. 1 is a front view of a bending machine embodying the present invention.

Fig. 2 is a plan view of the, machine shown in Fig. 1.

Fig. 3 is a fragmentary plan view of the maassigner to Briggs Detroit, Mich., a corchine shown in Figs. 1 and 2 at the beginning of the bending operation.

Fig. 4 is a fragmentary side view of the machine showing the form plate and the roller over which the form plate rolls to effect curvature in the vertical plane,

Fig. 5 is a sectional view of the form plate and its guiding means, said view being taken in the direction of the arrows on the section plane passing through the section line 5 5 of Fig. 1.

Fig. 6 is a fragmentary bottom view of the machine illustrating the swinging arms and their actuating mechanism.

Fig. 7 is a perspective view of a bent workpiece.

Fig. 8 is an enlarged transverse sectional View through the workpiece, said view being taken in the direction of the arrows on the section plane passing through the line 8 8 of Fig. 7.

Fig 9 is a plan view of a modied structure embodying the present invention.

Fig. 10 is a side view of the machine shown in Fig. 9.

Before explaining in detail the present invention'it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation, and it is not intended to limit the invention claimed herein beyond the requirements of the prior art.

In the drawings there is shown, by way of example, an improved bending machine embodying the present invention. The invention is illustrated and described as embodied in a bending machine adapted for bending window frame moldings for motor vehicle bodies. However. it will be understood that the invention may be successfully applied to machines adapted for bending other relatively long workpieces to threedimensional curvatures or two-dimensional curvatures, if desired. The machine herein illustrated and described is of the horizontal type and includes a form plate moving in a horizontally extending plane. It will be understood, however, that vertical machines may also be constructed in accordance with the present invention,

Referring' to the drawings and Particularly to Figs. 1 to'8 thereof, the machine illustrated there- -inv comprises a supporting frame or table 20 havat any desirable height. On the plate 2| there is mounted a power cylinder 22 having a piston 23 slidably iitted therein. Actuating fluid such as compressed air or oil is admitted to the cylinder 22 through a m-ain conduit 24 and one of the branch conduits 24a or 24h, said branch conduits having their outer ends connected with the cylinder 22 on the opposite sides of the piston 23, and their inner ends communicating with the main conduit 24 through a control valve 25. By properly manipulating the control Valve 25 the actuating iluid may be admitted into the cylinder 22 on the left-hand side of the piston 23 moving the same toward the right, while the fluid entrapped in the Icylinder on the opposite side of the piston is permitted to escape through the conduit 24a and control valve 25 into an exhaust tank (not shown).

To the piston 23 there is secured one end of a piston rod 26 passing through a cover 21 of the cylinder 22, wherein suitable packing means are provided to prevent leakage of the fluid around the piston rod 26. The opposite end of the pis- Y. ton-rod 26 is secured to an angular bracket 28 having an extension or tail 28a sliding in a slot provided in a block 29 mounted on the top plate 2 Retainer strips 29a are provided on the block 29 to retain the extension 28a in said slot. To the block 28 is hingedly connected as shown at 30 a form plate 3| supported from underneath by a pair of spaced rollers 32 mounted respectively in two supporting brackets 32a secured to the tcp plate 2|. The form plate 3| moves in a horizontally extending plane lbut is provided in side view or in the vertical plane with a deilnite curvature, as is clearly shown in Figs. 1 and 4, in order to impart three-dimensional curvature to the workpiece received by a track 33 provided around the periphery of the form plate 3|. 1n the present embodiment of the invention said track is provided at the three sides of the form plate 3|. To the bracket 28 there is secured a push plate 34 provided with a curved surface 34a engaged by two push rollers 35 secured to the plate 3|. The curvature of the surface 34a in the vertical plane is determined by a radius equal to the distance between the axis of the hinge 30 and the surface contacting points on the rollers 35.

It will now be clear in view of the foregoing that as the piston 23 moves to the right, the push plate 34 exerts force on the rollers 35, thus moving the form plate 3| in the salme direction. Because of the provision of the straight slot in the block 29, the path of the form plate 3|, when viewed in the plan view thereof, will be rep-resented by a straight line, while in the side view thereof, as can be clearly understood from an examination of Fig. 4, the form plate 3| rolls over the supporting rollers 32, the push rollers 35 rolling up over the surface 34a.

Pressure means acting on the workpiece are exemplified inthe present embodiment by two pressure shoes 36 carried by slide blocks 31 sliding in guideways formed in the swinging arms 38 operatively mounted on the supporting plate 2|. The blocks 31 are actuated with the aid of uldactuated pressure cylinders 39 having suitable pistons (not shown) slidably fitted therein in a manner well known in the art and connected to said blocks with the aid of piston rods 40. The pressure shoes 36 are connected to the sliding blocks through pins 4| on vwhich pins the shoes can rock laterally or horizontally within predetermined limits to follow the curvature of the ingu' horizontally extending top plate 2 l' situated form plate 3| in the plan view, and to move on said pins 4| longitudinally thereof or in a vertical direction within predetermined limits in order to be able to follow the side curvature of the form plate. Thus, in eiect, the connections between the sliding blocks 31 and the pressure shoes 36 are of a substantially universal nature, giving flexibility to the pressure shoes 36 in all necessary directions.

` Means effecting swinging of the arms 38 are illustrated in Fig. 6. Referring to said figure, Said means including a cylinder 42 having a fluidactuated piston slidably tted therein and controlled with the aid of uid transmitting conduits 43a and 43D in a manner similar to that described in connection with the power cylinder 22. The piston rod 44 of said cylinder is connected toa cross head 45 having a pin 46 slidable in slots 41 provided in sub-arms 48 rigidly connected to the arms 38 through shafts 49 journalled in the plate 2| for rotation therein. As the cross head 45 moves to the right, the pressure of the pin 46 causes the Sub-arms 48 to assume the respective angularly related positions indicated in Fig. 6 in broken lifnes which, in turn, cause the swinging arms 38 to open and move from the positions indicated in dotted lines to positions indicated in broken lines in said Fig. 6.

The operation of the machine is illustrated in Figs. 2 and 3. As shown in Fig. 3, the workpiece 50 is placed by its middle portion in the workpiece-receiving track 33 at the head oi' the U- shaped contour. Under this condition, the swinging arms 38 are parallel to each other. By admitting iiuid under pressure into pressure cylinders 39 in conventional manner, such as through flexible conduits 39a, the pressure shoes 36 are caused to move toward the form plate 3|, bending the workpiece 50 by pushing the same into said track. Thereupon, the control valve 25 of the power cylinder 22 is manipulated to cause the form plate to move to the right or toward the pressure shoes. At the same time the control valve of the swinging arms cylinder 42 is manipulated to admit iiuid under pressure therein, moving the piston of cylinder 42 and piston rod 44 to the right, thereby causing the swinging arms to open and to carry the pressure shoes 36 around the form plate and along the legs of the U-shaped contour thereof, thereby effecting bending of the workpiece. Rolling of the form plate 3| over the supporting rollers 32 permits incorporation of relatively large side curvature into said plate and consequently into the workpiece without excessive vertical movement of .the pressure shoes 36. It is preferable to construct the machine in such a way that movement of the pressure shoes in the direction of the guideways caused by the rotation of the swinging arms 29 is relatively small, the bending being achieved mainly by the movement of the form plate 3| toward said pressure shoes.

By virtue of the above described construction, there is provided a machine in which bending of the workpiece 50 to a three-dimensional curvature is effected with the aid of comparatively simple relative movements of the form plate 3| and pressure shoes 36. Carrying of the pressure shoes 36 around the plate greatly reduces the friction which might be produced in bending by direct pressure of the pressure shoes on the workpiece, thereby making the bending operation much easier and less harmful to the surface of the workpiece.

Figs. 9 and 10 illustrate a modied construction of the machine in which the swinging arms 38 are replaced by stationary guideways 5I mounted on the plate A2| at an angle to each other. In guideways 5| slide blocks 52 are adapted to slide, these blocks having pressure shoes 53 pivotally mounted thereon in a manner corresponding and similar to the blocks 31 and pressure shoes 36, respectively, of the machine illustrated in Figs. 1 to 8 inclusive. In its other features the machine of Figs. 9 and 10 is substantially similar to the machine of Figs. 1 to 8. The modied machine may be employed where the curvature of the workpiece in the plan view thereof and the friction between the pressure shoes and the workpiece are not great, and swinging of the arms carrying the pressure shoes may be eliminated.

It should be understood that the machine described in Figs. 1 to 8 inclusive may be used with arms 38 remaining stationary in which the angle of the arms is determined experimentally for a given curvature. Fixing of the arms v 38 may be done with the aid of suitably provided pins locking the piston rod 44, or in any other suitable way.

The form plate 3i in both embodiments is interchangeable and may be changed to effect bending of different workpieces. This feature is very valuable since in conventional practice when various cams and levers are employed a machine is built for a denite curvature which cannot be changed.

I claim: 1. In a bending machine, a fluid-actuated piston, a form plate connected to said piston, guide means for guiding said form plate in a path projecting as a straight line in the plan view of the form plate, a peripheral track on said form plate adapted to receive a workpiece, means for swinging said form plate and track, two pressure shoes adapted to contact the workpiece and to force the same into said track for bending the workpiece, two duid-actuated pistons movable each along a straight line path, hinge means connecting each pressure shoe with a fluid-actuated piston, and means adapted to move said pressure shoes along said track to facilitate the relative movement of said track and said shoes during swinging movement of the track.

2. In a bending machine, a form plate, a power cylinder, a fluid-actuated piston slidably tted therein, a piston rod connecting said piston with said form plate for simultaneous motion, guide means adapted to guide said form plate in a straightlpath, a substantially U-shaped track on said form plate adapted to receive a workpiece, means for swinging' said form plate and track, two pressure shoes adapted to contact the workpiece at the head of said track and to exert bending pressure thereon forcing the ends of the workpiece into the leg portions of `said track, and two swinging arms adapted to carry said pressure shoes and to move them during bending operation from the headv of said track toward the ends of the legs thereof during the swinging movement of the track.

3. 'In a bending machine, a form plate, a power cylinder, a fluid-actuated piston slidably fitted therein, a piston rod connecting said piston with said form plate for simultaneous motion, guide means adapted to guide said form plate in a straight path, a peripheral track on said form plate adapted to receive a workpiece, two swingable arms, two pressure shoes carried by said arms and hingedly connected thereto, uid-actuated means carried by said arms .and exerting bending pressure on said shoes in the direction parallel to the longitudinal axes of said arms, and means for swinging said arms, as the plate is moved, around said plate to maintain substantially perpendicular direction of said bending force with respect to said track.

4. In a bending machine, a form plate, a power cylinder, a fluid-actuated piston slidably fitted therein, a piston rod connecting said piston with said form plate for simultaneous motion, guide means adapted to guide said form plate in a. straight line path, a peripheral track on said form plate adapted to receive a workpiece, two swinging arms, two pressure shoes carried by said arms and hingedly connected thereto, uidactuated means on said arms adapted to exert pressure on said shoes, means independent of said form plate for moving said arms to carry said shoes from the intermediate portion of the workpiece toward the ends thereof.

5. In a bending machine, a form plate, a power cylinder, a fluid-actuated piston slidably .tted therein, a piston rodconnecting said piston with said form plate for simultaneous motion, guide means adapted to guide said form plate in a straight line path, a peripheral track on said form plate adapted to receive a workpiece, two swinging arms, duid-actuated means for moving said arms, two pressure cylinders carried by said arms each having a slidably tted piston, two pressure shoes hingedly connected to said pistons and movable therewith along a straight line path relative to said arms, said shoes being further adapted to contact the workpiece and to exert bending pressure thereon as said form plate is moved toward said shoes and said shoes are swung in a predetermined path.

6. In a bending machine, a supporting frame,

a power cylinder mounted on said frame and.

having a fluid-actuated piston slidably fitted therein, a straight guideway formed on said frame, a form plate having a workpiece-receiving track, said plate being adapted to move along said guideway, means connecting said form plate and said piston for simultaneous movement, two guide arms hingedly mounted on said frame, each of said arms having a fluid-actuated member sliding therein and a pressure shoe hingedly connected to said member and adapted to exert bending pressure on -said workpiece, and fluid-actuated means forswinging said guide arms around said plate as the same is moved along said guideways in order to exert on said pressure shoes forces for moving them along said track.

7. Ina bending machine, a support, a form plate mounted on the support and having a workpiece-receiving track curved in side view, means for reciprocating said support, means for hinging the plate to the support, means for sup-porting the plate for pivotal movement as it is reciprocated, and pressure means for progressively bending the workpiece on said track during movement of said plate.

8. In a bending machine, a support, a form plate mounted on the support and having a generally `U-shaped workpiece-receiving track curved in side View. means for reciprocating said support, means for hinging the plate to the support', means for supporting the plate for pivotal movement as it is reciprocated, and pressure means for progressively bending the Workpiece on said track during movement of said plate, said pressure means comprising spaced iiuid pressure actuated shoes movable in opposite directions along the track.

9. In a bending machine, a generally U-shaped track member curved in side view and upon which a workpiece is adapted to be progressively bent, spaced pressure shoes movable in opposite directions along the track, and means for shifting the track member toward the shoes and also for swinging the track member during the bending of said workpiece,

l0. In a bending machine, a supporting frame, a form plate slidably mounted on said frame and provided with a peripheral workpiece-receiving track of three-dimensional curvature, guide means mounted on said frame and adapted to guide said plate in a path projecting as a straight line in the plan view of the form plate, a bodily stationary roller engaging the form plate underneath thereof, the bottom surface of said plate being curved in order to impart a curva-l ture to said path to conform substantially to the side View curvature of said track, two pressure shoes adapted to contact" said workpiece and to exert bending pressure thereon, two fluidactuated headblocks slidably mounted on said frame, and universal connections between said headblocks and said shoes.

11. In a machine for bending relatively long workpieces to three-dimensional curvature, a curved movable form plete having a workpiece receiving track of three-dimensional curvature, an angular bracket movable along a .straight line path, a fixed roller contacting said plate from underneath, a hinge on one end of said plate connecting the same to the horizontal leg of said bracket, and a roller on the other end of said plate, said roller being adapted to roll on the vertical leg of said movable bracket, and a pressure shoe adapted to force a workpiece in said track and to follow the same.

l2. In a machine for bending relatively long workpieccs, a movable form plate having a workreceiving track of three-dimensional curvature, pressure means adapted to press the workpiece against the track progressively as the plate is moved against said pressure means, means for moving said form plate along a path projecting in plan view of the plate as a straight line,`means for swinging said form plate, and means for moving said pressure means along said workpiece independently of the movement of said form plate during the swinging movement thereof.

13. In a machine for bending relatively long workpieces to predetermined curvature, a movable form plate having a generally U-shaped workpiece-receiving track, a pressure shoe adapted to press the workpiece onto the track for bending as said plate is moved against said shoe, means moving said plate toward and away from said shoe, means for swinging said form, plate and track, and means moving said pressure shoe from the head of said track toward the end of a leg thereof, said last means being adapted to actuate said pressure shoe independently of the motion of said plate during the swinging movement thereof.

14. In a machine for bending relatively long workpieces to predetermined curvature, a movable form plate having a generally U-shaped workpiece-receiving track, two pressure shoes adapted to press the workpiece Onto the track for bending, means for moving said plate toward and aw 1y from said shoes, means for swinging said form plate and track, and means moving said shoes along the track beginning from the head of the track toward the ends of the legs thereof and independently of the movement of said plate during the swinging movement of the plate and track.

15. In a machine for bending relatively long workpieces to a predetermined curvature, a movable form plate having a generally U-shaped workpiece-receiving track, two pressure shoes adapted to press the workpiece onto the track for bending, means for moving said plate toward said shoes to produce a relative movement of said track and said shoes, means for swinging said form plate and track, and two swinging arms carrying said shoes and adapted to move them in opposite directions along said track from the head of said U-shaped track toward the ends of the legs thereof thereby facilitating the relative movements of ,said shoes and said track during the swinging movement of the track.

16. In a machine for bending relatively long workpieces to a predetermined curvature, a movable form plate having a generally U-shaped workpiece-receiving track, two fluid-actuated pressure shoes adapted to press the workpiece onto the track for bending, duid-actuated means for moving said form plate toward and against said shoes to effect relative pressure and movement between said track and shoes, two fluidactuated swinging arms carrying said shoes and their actuating means and adapted to move said shoes simultaneously in opposite directions beginning substantially from the head of said track toward the ends thereof thereby facilitating the relative movements of said pressure shoes and said track.

17. In a bending machine, a workpiece-receiving track curved in side view, means for moving the track bodily in a forward direction, pressure means for progressively pressing the workpiece against the track during said movement, means for shifting the pressure means during the forward movement of the track, and means for imparting a pivotal motion to the track to cause said pressure means to follow the curvature of said track.

18. In a machine for bending relatively long workpieces to three-dimensional curvature, a form plate havingV a workpiece-receiving track of three-dimensional curvature, a pressure shoe adapted to Contact the workpiece and to force it yieldingly against said track for bending, said pressure shoe being further adapted to follow said track, means for moving said form plate against said shoe to cause relative movement thereof, and means for eiecting limited bodily rotation of said form plate in a plane substantially perpendicular to its 'movement against said shoe.

19. In a machine for bending relatively long workpieces to three-dimensional curvature, a support, a form plate having a workpiece-receiving track of three-dimensional curvature and an end hinged to said support, a pressure shoe adapted to contact the workpiece and to force it yieldingly against said track for bending, said pressure shoe being further adapted to follow said track, means for moving said support and, consequently, said form plate against said shoe to cause relative movement thereof, and guiding means for said plate adapted to effect limited bodily rotation of said plate around its hinge.

20. In a machine for bending relatively long workpieces t0 three-dimensional curvature, a horizontally movable support. a form plate having a.

peripheral workpiece-receiving track of threedimensional curvature and an end hingedly connected to said support, a pressure shoe adapted to contact the workpiece and to force it yieldingly against said track for bending, said pressure shoe being further adapted to follow said track, means for moving said form plate horizontally against said pressure shoe, and guiding means cooperating with said plate to eiect bodily rotation thereof in a vertical plane during said horizontal motion.

21. In a machine for bending relatively long workpieces to three-dimensional curvature, a horizontally movable support, a form plate having ,a peripheral workpiece-receiving -track of three-dimensional curvature and an end hingedly connected to said support, a pressure shoe adapted to contact the workpiece and to force it yieldingly against said track for bending, said pressure shoe being further adapted to follow said track, means for moving said form plate horizontally against said pressure shoe, and a stationary support for said plate engaging said form plate, the surface of said form plate engaged by said support forming an angle with the horizontal to eiect a bodily rotation of said form plate in a vertical plane during said horizontal movement.

22. In a machine for bending relatively long workpieces to three-dimensional curvature, a horizontally movable support, a form plate having a peripheral workpiece-receiving track of three-dimensional curvature and an end hingedly connected to said support', a pressure shoe adapted to contact the workpiece and to force it yieldingly against said track for bending, said pressure shoe being further adapted to follow said track, means for moving said form plate horizontally against said pressure shoe, and a bodily stationary roller adapted to engage said plate from the underneath, and to effect a bodily rotation of said form plate in avertical plane during said horizontal movement.

23. In a machine for bending relatively long workpieces to three-dimensional curvature, a movable support, a form plate having a peripheral work-receiving track of three-dimensional curvature and a curved bottom surface, said form plate having one free end and another end hinged to said support for limited bodily rotation in a plane substantially perpendicular to the plane of motion of said support, a pressure shoeadapted to contact the workpiece and to force it yieldingly against said track for bending, said pressure shoe being mounted for limited rocking movement in order to follow the curvature of said track, means for moving said support and consequently said plate against said pressure shoe, and a stationary roller engaging said form plate at its curved bottom surface.

24. In a machine for bending relatively long workpieces to three-dimensional curvature, a movable support, a form plate having a peripheral work-receiving track of three-dimensional curvature and a curved bottom surface, said form plate having one free end and another end hinged to said support for limited bodily rotation in a plane perpendicular to the plane of motion of said support, a pressure shoe adapted to contact the workpiece and to force it yieldingly against said track for bending, said pressure shoe being mounted for limited rocking movement in order to follow the curvature of said track, means for moving said support and consequently said plate against said pressure shoe, a stationary roller engaging said form plate at its curved bottom surface, a second roller secured to said free end, and a curved tracksecured to said support and engaged by said second roller in the bodily rotation of said form plate.

25. In a machine for bending relatively long workpieces to three-dimensional curvature; a horizontally movable support, a form plate having a peripheral work-receiving track of generally U-shape and of three-dimensional curvature, said form plate being curved in its side view and having one end free and another end hingedly connected to said support for limited bodily rotation in a vertical plane, two pressure shoes adapted to contact the workpiece and to force it yieldingly against said track for bending beginning from the head of the track and toward the ends thereof, said pressure shoes being mounted for limited rocking movement in order to follow the curvature of said track, means for moving said support and consequently said form plate horizontally against said pressure shoes, and a stationary roller engaging said form plate at its curved surface to cause bodily rotation thereof in a vertical plane around said hinge during said horizontal movement.

26. In a machine for bending relatively long workpieces to three-dimensional curvature, a horizontally movable support, a form plate having a peripheral generally U-shaped workpiecereceiving track of three-dimensional curvature, hinge means connecting one end of said plate to said support for limited rotation in a vertical plane, two fluid-actuated pressure shoes adapted to press the workpiece against the track for bending, fluid-actuated means for moving said form plate against said pressure shoes to effect relative pressure and movement between said track and said pressure shoes, two fluid-actuated swinging arms carrying said shoes and their actuating means and adapted to move said pressure shoes along said track simultaneously in opposite directions beginning substantially from the head of said track and toward the ends thereof, and guiding means associated with said plate and adapted to effect during said horizontal movement a predetermined bodily rotation of said form plate in a vertical plane.

27. In a machine for bending relatively long workpieces to three-dimensional curvature, a horizontally movable support, a form plate having a peripheral generally U-shaped workpiecereceiving track of three-dimensional curvature, hinge means connecting one end of said plate to said suppoit for limited rotation in a vertical plane, twoiluid-actuated pressure shoes adapted to press the workpiece against the track for bending, duid-actuated means for moving said form plate against said pressure shoes to eiect relative pressure and movement between said track and said pressure shoes, two fluid-actuated swinging arms carrying said shoes and their actuating means and adapted to move said pressure shoes along said track simultaneously in opposite directions beginning substantially from the head of said track and toward the ends thereof, and a stationary roller engaging said form plate from underneath, the surface engaged by said roller forming in the side view of the plate a line disposed at an angle with the line of travel of said form plate.

28. In ,a machine for bending relatively long workpieces to three-dimensional curvature, a. horizontally movable support, a form plate having a peripheral generally U-shaped workpiecereceiving track of three-dimensional curvature, binge means connecting one end of said plate to said support for limited rotation in a vertical plane, two iuid-actuated pressure shoes adapted to press the workpiece against the track for bending, huid-actuated means for moving said form plate against said pressure shoes to eiect relative pressure and movement' between said track and said pressure shoes, two Huid-actuated swinging arms carrying said shoes and their actuating means and adapted to move said pressure shoes along said track simultaneously in opposite directions beginning substantially from the head of said track and toward the ends thereof, and -a stationary roller engaging said form plate from underneath, the under surface of said form plate engaged by said rollers being curved in side View of the form plate.

29. In a bending machine, a form plate, a power cylinder, a uid-actuated piston slidably fitted therein, a piston rod connecting said piston with said form plate for simultaneous motion, guide means adapted to guide said form plate in a straight path, a peripheral track on said form plateadapted to receive a workpiece, means for swinging said form plate and track, a pressure shoe adapted to contact the workpiece and to exert bending pressure thereon as the form plate is moved to and past said. shoe, a swinging arm adapted to carry said shoe, means for swinging said arm independently of the travel of the form plate and during the swinging motion thereof, and means for sluiting the shoe longitudinally of the arm.

1 30. In a bending machine, a form plate, a power cylinder, a fluid-actuated piston slidably tted therein, a piston rod connecting said piston with said form plate for simultaneous motion, guide means adapted to guide said form plate in a straight path, a peripheral track on said form plate adapted to receive a workpiece, means for swinging said form plate and track, two pressure shoes adapted to contact the workpiece and to exert bending pressure thereon as the form plate is moved to and past said shoe, two swinging arms adapted to carry said pressure shoes and to move the same from the middle portion of the workpiece toward the ends thereof for bending said workpiece, means for swinging said arms independently of the form plate and during the swinging motion thereof, and means for shifting said shoes longitudinally of the arms.

PAUL F. MAIZE. 

